1. Field of the Invention
The present invention relates to a sheet storing apparatus, in particular, a sheet storing apparatus for storing therein sheets havIng an image formed thereon by a copying machine and subsequently refeeding the stored sheets to the copying machine.
2. Description of Related Art
Recently, there have been provided various sorts of copying machines having automatic duplex/composite copying functions. These copying machines employ a sheet storing arrangement for storing the sheets having an image formed on one side thereof prior to the sheets being refed, such that the sheets are horizontally placed at a location under the image forming unit of the copying machine or at a location adjacent one side of a sheet discharge port. However, the former arrangement has the disadvantages that the mechanism for dealing with sheet jamming is complicated and that the apparatus requires high rigidity and inevitably the copying machine itself must be of a large size. The latter arrangement requires a large floor space and, especially where a sorter or the like are connected thereto, a very large space is required for installation.
In order to overcome these difficulties, it may be conceivable to adopt an arrangement such that sheets are placed at one side of the discharge portion of the copying machine by piling them generally vertically in the thicknesswise direction thereof. However, such vertical placement of sheets involves a problem that sheets are liable to buckle, which may act as a resistance factor upon subsequent placement of sheets and result in defective placement, placement failure, defective refeed, or refeed failure.
With sheet feeding apparatus or refeeding apparatus for one-side copied sheets in a copying machine, it is necessary that a plurality of sheets laid one over another must be fed forward accurately one by one. In the prior art, therefore, for example, as disclosed in Japanese Utility Model Unexamined Publication No. 57-203037, a sheet separation unit is employed such that a resilient member is pressed against a power drive roller so that a second and subsequent sheets which may tend to accompany a first sheet are halted by the friction force of the resilient member. However, such sheet separation unit involves a problem that after the first sheet is fed forward, the front ends of the second and subsequent sheets may remain as it is carried between the roller and the separation resilient member, thus causing duplicate feed.